Technique Monitoring Physical Stability Explained

The size of the particles in relation to the particles in the continuous phase, not whether precipitation occurs, and the existence of Brownian motion are all used to classify dispersions. Suspensions are dispersions of large enough particles to allow sedimentation, whereas colloids and solutions are dispersions of smaller particles.

Dispersion Stability

Dispersions are thermodynamically unstable; yet, they can be thermodynamically stable for long periods of time, which defines their shelf life. This time period must be tracked in order to assure the highest possible product quality for the end-user. “The ability of a dispersion to withstand changes in its qualities over time is known  as dispersion stability.”

Destabilisation phenomenon of a dispersion

There are two basic processes that cause these destabilizations:

Migration phenomena: The density difference between the ongoing and dispersed phases causes gravitational phase separation.

• When the dispersed phase is less thick than the continuous phase, creaming occurs (e.g. milk, cosmetic cream, soft drinks, etc.)
• When the phase separation is denser than the continuous phase, it is called sedimentation (e.g. ink, CMP slurries, paint, etc.)

Particle size increase phenomena: where the dispersed phase (drops, particles, bubbles) grows in size

• Reversibly
• Irreversibly

Technique Monitoring Physical Stability

The most extensively used technique for monitoring a product’s dispersion status and recognising and quantifying destabilisation processes is multiple light scattering combined with vertical scanning. It works with intense dispersions that haven’t been diluted. Light is backscattered by the particle/droplets when it passes through the sample. The size and size distribution of the dispersed phase is directly related to the backscattering intensity. As a result, both local and global changes in size and concentration are identified and tracked.

Methods for shelf-life protection

Here are some of the ways for shelf life protection: 

Direct Methods

The method in which the product is stored under similar conditions as those in the field and its evolution is tracked at regular intervals. The main benefit of this method is that it produces a very accurate estimate of how long it takes for a commodity to deteriorate. Nevertheless, these studies typically take a while and do not consider the fact that product storage conditions are not consistent over time.

Challenge Test

This method entails inadvertently introducing diseases or microbes into food during the manufacturing process, exposing the product to the conditions it will face on the field. The main issue of this test is that it considers only the impacts of the examined parameters, and overlooks the fact that the thing may be exposed to several influences simultaneously. Furthermore, these are investigations that are both complicated and difficult to carry out.

Accelerated Shelf Life Test

Temperature, oxygen pressure, and moisture content are all altered in these experiments to speed up the spoiling responses of a product. These predictions help one to forecast how foods will behave under various settings and anticipate their change over time. Accelerated testing allows the addition of changing environmental circumstances as well as variations in the concentrations of the substances they are made up of. These studies are extremely flexible, low-cost to the manufacturer, and provide an assessment of several scenarios. There is some error margin in the produced results because it is not a perfect representation of reality.

Survival Method

It is a sort of research based on a consumer’s perception of a product’s physical qualities. This strategy attempts to establish a link between the product’s shelf life and its perceived quality. Although it is not a reliable approach for estimating the shelf life, it is necessary to use it in conjunction with other methods to determine a product’s best by date.

Microbiology Testing

Based on modelling and simulation, this research investigates the various microbial reactions of foods to diverse environmental conditions to anticipate the behaviour of the microbes in the product. This form of analysis, which is commonly employed when designing a new product, considers the product’s possible changing conditions; nevertheless, it has two key drawbacks: it adds complexity to the manufacturer’s work and the conclusions are based on a simulation that may or may not be correct.

Conclusion

This technique is visible in solutions, suspensions and colloids. It is among the important factors for monitoring the physical stability of the dispersion medium and dispersed phase. These factors help in identifying the use cases of different solutions and colloids and effectively using them.